fix+ux v1.15.1: display-settings round from live usage

- comfort bounds: parseFloat+isFinite guard (empty input collapsed a bound to 0
  and the auto-swap made 'comfort from 25' behave as 0-25 → green at 24°)
- avg room temperature in the room tooltip (what the temp fill actually uses)
- hover darkens the current fill instead of recoloring blue; grey when unfilled
- fill mode as a radio group with short labels; compact inline bounds inputs
- space dialog widened to 500px; TESTING.md updated in the same commit

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "houseplan-card",
-  "version": "1.14.0",
+  "version": "1.15.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "houseplan-card",
-      "version": "1.14.0",
+      "version": "1.15.0",
       "license": "MIT",
       "dependencies": {
         "lit": "^3.1.3"